Safety control for absorption refrigeration machines



Jan- 15, 1952 H. LEONARD, JR 2,582,837

SAFETY CONTROL FOR ABSORPTION REFRIGERATION MACHINES Filed March 31, 1949 3 Sheets-Sheet l OOOOOOOOOOOOOOOO O O O O O O O O O O O INVEN TOR.

H (M y,

Jan. 15, 1952 H. LEONARD, JR

SAFETY CONTROL FOR ABSORPTION REFRIGERATION MACHINES Filed March 51, 1949 3 Sheets-Sheet 2 INVENTOR.

Jan. 15, 1952 L. H. LEONARD, JR

SAFETY CONTROL FOR ABSORPTION REFRIGERATION MACHINES Filed March 31, 1949 Illll IHII'TYIYHIIII H11]! 11 I5 Sheets-Sheet 5 INVENTOR. 4 fliW Patented Jan. 15, 1952 SAFETY CONTROL FOR ABSORPTION REFRIGERATION MACHINES Louis H. Leonard, Jr., Syracuse, N. Y., assignor to Carrier Corporation, Syracuse, N. Y., a corporation of Delaware Application March 31, 1949, Serial No. 84,702

9 Claims.

This invention relates to absorption refrigeration systems and more particularly to an absorption refrigeration system including a safety control for discontinuing operation of the system in response to a predetermined increase in temperature of refrigerant leaving the evaporator of the system indicating failure of the various pumps and motors required in connection with the operation of the system or of the various control devices employed in connection'with the system.

The chief object of the present invention is to provide an absorption refrigeration system including pneumatically operable control means and means for preventing the operation of at least some ofsuch control means in response to a'predetermined increase in temperature of refrigerant leaving the evaporator, failure of various pumps, shortage of absorbent solution or increase in'the absolute pressure in the absorber shell.

An object of the invention is to provide an absorption refrigeration system including pneumatically operable control means and a solenoid. valve disposed in the compressed air supply line, the electrical circuit to the solenoid valve being broken in response to a predetermined increase in temperature of refrigerant leaving the evaporator on failure of various'pumpsshortage of absorbent solution or increase in the absolute pressure in theabsorber shell, thereby closing the solenoid valve to discontinue the supply of compressed air to at least some of the controls of the system and to vent such compressed air to atmosphere.

A further object is to provide an absorption refrigeration system including pneumatically operable control means and a safety control adapted to discontinue the supply of heating medium to the generator and supply cooling medium to the absorber and condenser upon a predetermined increase in temperature of refriger-- ant leaving the evaporator which reflects a failure or improper operation of the refrigeration system. Other objects of my invention will be readily perceived from the following description.

This invention relates to an absorption refrigeration system comprising in combination an evaporator, an absorber, a generator and a condenser disposed in a closed circuit, means to regulate flow of solution through the circuit, means for regulating the supply of heating medium to the generator, means for regulating the supply of cooling medium to the absorber and to the condenser, a pneumatic supply system. for actuating said regulating means and means for venting at least a portion of the pneumatic supply system to the atmosphere to discontinue operation of the absorption refrigeration system.

The attached drawings illustrate a preferred embodiment of my invention in which:

Figure 1 is a diagrammatic view of an absorption refrigeration system including the present safety control;

Figure 2 is a diagrammatic view illustrating the control arrangement for the absorption refrigeration system shown in Figure 1; and

Figure 3 is a view in elevation illustrating a manometer for use as a primary control.

Referring to the attached drawings, there is shown a shell 2 in which is disposed a coil 3 which cooperates with the shell to form an absorber. A pan-like member 4 is disposed in shell 2 above the absorber and cooperates with the shell to form an evaporator. A second shell 5 is disposed above shell 2; a coil 6 is provided in shell 5 which cooperates therewith to form a generator or boiler. A second shell '1 is disposed above the generator in shell 5 and cooperates with the shell to form a condenser.

Weak solution is withdrawn from absorber 3 by pump 8 through line 9 and is forwarded to generator 6 through line 10, heat exchanger H and line I2. Strong solution is withdrawn from generator 6 through line I3, overflow arrangement l4, line 15, heat exchanger H, and line 15 to ejector [1 which forwards strong solution through line Hi to absorber 3. Arrangement I4 prevents solution in generator 5 rising above or sinking below a predetermined level and. aids in maintaining a desired head upon ejector IT.

A pump l9 passes cooling water through line 29 to the coil of absorber 3 and then forwards the water after its passage through absorber 3 through line 2| to the coil of condenser I, such water leaving the condenser through line 22.

A line 23 permits the withdrawal of vapor condensate from condenser I, the condensate passing through a precocler 24 and then being returned to evaporator 4. A suitable purge arrangement, described and claimed in the co pending application of Alexis A. Berestneff, Serial No. 29,527, filed May 27, 1948, now Patent No. 2,520,027, dated August 22, 1950, is provided to purge condenser I and absorber 3 of noncondensible gases.

Chilled water treated by the system is withdrawn from evaporator 4 by pump 23 through line 21, and is circulated through line 28 to an air conditioning device (not shown) and is returned to the evaporator 4 through line 28'. The returned water is sprayed in evaporator 4, being flash-cooled, the flashed vapor passing downward to be absorbed by solution in the absorber 3 while the chilled water is withdrawn from evaporator 4, as described above. Such system is described and claimed in the co-pending application of Alexis A. Berestneff, Serial No. 683,387, filed July 13, 1946, now Patent No. 2,565,943, dated August 28, 1951. Reference is made to such application for a more complete description of the absorption refrigeration system.

A suitable control arrangement for such absorption refrigeration system is shown in detail in the co-pending application of Alexis A. Berestneff and William L. McGrath, Serial No. 683,390, filed July 13, 1946, now Patent No. 2,565,838, dated August 28, 1951, and reference is made thereto for a description of the details of the control arrangement. The control arrangement includes a valve 29 disposed in the solution line connecting pump 8 and heat exchanger Such valve 29 is regulated by a thermostat 30 operable in response to changes in load conditions reflected for example, by a bulb disposed in or adjacent line 21 reflecting the temperature of chilled water leaving the evaporator. Valve 29 and thermostat 30 are connected to a pneumatic supply system 3| hereinafter described.

A valve 32 is disposed in line 22 to regulate passage of condensing water through the absorber and the condenser. Valve 32 may comprise a normally closed butterfly valve operable by a motor connected to pneumatic supply system 3| and regulated by means of a control 33 reflecting saturated temperature corresponding to pressure in shell 5.

Valve 34 regulates passage of steam to the generator. Valve 34 is governed by a control 35 connected to pneumatic supply system 3|; and actuated in response to temperature of solution leaving the generator 6 as reflected by bulb HE.

A reset control 36 is provided to reset control 35 in response to the difference in compressed air pressure in the lines connecting valve 29 with thermostat 39 and control 33 with valve 32.

A dilution tank 31 is disposed adjacent shell and is connected by line 38 to a three-way valve 39 connected to pneumatic supply system 3|. This three-way valve 39 is connected by line 40 to the discharge side of pump 25. It is also connected by line 4| to solution line l5. Upon startup of the system, pump 26 fills tank 31 with water; vhen operation of the system is discontinued valve 39 shifts to a second position and permits water in tank 3'! to be returned to the system through line 4|. The arrangement for diluting the system upon shutdown is described and claimed in the co-pending application of Alexis A. Berestneff, Serial No. 65,432, filed December 15, 1948.

The present invention is concerned pn'marily with a safety control effective to discontinue operation of the system upon failure of various control elements, pumps or motors which might interfere with operation of the system. If a failure in the system occurs, the temperature of chilled water leaving the evaporator rises so that a predetermined increase in temperature of chilled water leaving the evaporator may be used as an indication of failure of various pumps, shortage of absorbent solution or increase in the absolute pressure in the absorber shell.

Referring to Figure 2, it will be noted that the supply air line of pneumatic supply system 3| is connected to a three-way solenoid valve 5|. Solenoid valve 5| may be a so-called electricpneumatic relay and includes three ports, A, B and C. Port A is connected to supply line 53; port C is connected through secondary line 52 to secondary line 53 which supplies compressed air to the various controls except control 33 and valve 29. Compressed air passes through control 35 and is supplied through a reversing relay 54 and a diverting switch or control 59 to regulate valve 34. The motor control valve 32 is also connected to line 53 by line 54. Control 33 is connected to line 55 connecting reset control 36 and the motor of valve 32. Reset control 38 is also connected to line 53 connecting valve 29 and thermostat 35. Thus the reset control is responsive to the difference in pressure in such lines to reset the operating point of valve 34.

Line 57 and a second line 58 connected thereto connects thermostat 39 directly with supply air line 58; valve 29 is connected to line 55 by line 51. Compressed air supplied to thermostat 3i] and valve 29 need not pass through the sole' noid valve 5|.

Three-way pneumatic valve 39 is also connected to line 53 so that it is actuated when solenoid valve 5| is energized. Bypass valves 82 and 83 hereinafter described around solenoid valve 5| are arranged so that three way valve 39 is not operated when valve 5| is out of action (valved off).

Solenoid valve 5| is connected to the electrical circuit of the system including the starter for chilled water motor 66, a three-position electric switch 61, a mercury contact switch 68 and intervening connections to solution pump, starter- 69 actuating motors H! and 10' to operate the solution pump and the condensing water pump and a pressure switch located adjacent the discharge of solution pump 8.

Mercury contact switch 68 is connected by capillary tube T2 to a bulb 13 disposed in or adjacent to the chilled water line 21. It will be noted (refer to Figure 2) that wire 15 connects a terminal of switch 68 with solenoid valve 5|. A second wire 16 connects wire 15 with a terminal of switch 61. A wire H also connects switch 58 with a second terminal of switch 61.

Considering the operation of the safety control, switch 6! has three positions, off, start and run. When such switch is in the off position. of course, the system is not in operation.

When switch 61 is in starting position, ports A and C of solenoid valve 5| are connected, permitting the supply of air to the various controls and valves 32, 33, 34 and 35, etc.; at such time mercury contact switch is not in operation being short circuited through wire 16. As soon as the temperature of the chilled water leaving the evaporator falls to a predetermined point the switch is placed in the run position and mercury contact switch 68 assumes control. The machine is then in so-called running condition. Assume,

- thereafter that, due to failure of some element of the control or machine, the temperature of chilled water leaving the evaporator rises to a predetermined point on failure of various pumps, shortage of absorbent solution or increase in the absolute pressure in the absorber shell. In such case switch 58 is opened, breaking the flow of current through solenoid coil 5|. Upon failure of current to solenoid valve 5|, ports A and C are disconnected, ports C and B being connected and permitting venting or bleeding of compressed amass:

air to surroundingatmosphere. whenthe. compressed :air is:vented' to the atmosphere, valves 82" and 84 are immediately moved to closedposition. Thechliled waterpump and the solution pumpcontinue" to operate-provided failure of either "did not cause the safety control" to function. Compressed-air continues, of course; to be supplied to valve 28 and itseontrol l0.

-When-yalves 32 and" are in closed' position vulve 39 moves" from oneposition" to a second position permitting tank S'I'to empty its contents throughline II to a'solution line. It is" desirable that the solution pump' continue to operate in order 1 to assure proper mixing of additional water-with solution in'..the s-ystem upon shut down. If solution pump motor orpump or chilled water'motor or pump switch 88 faIL'the-electrical circuit isautomatically' broken to discontinueoperation of the system.

Referring'to Figure 2 it-wi1l be noted-that a manual switch 88 is provided-which is connected to line 53. By-pass line BI is also provided conneeting line 53 with the main supply 1ine 50. A valve'82 is disposed in'line 8|. "It willbe noted a second valve'83- is disposed in line -52 connecting solenoid v'alve'il with-line'-53. Under some conditions it-may be desirable to by-pass solenoid'valve 5|; by-pass line 8| and valve 82 therein permit solenoid valve 5| to be bypassed. Valve 83 assures that compressed air supplied to line 53'under such conditions does not escape through ports 3- andC of solenoid valve 6|.

,If desired a-manometer 85 may be placed-in the" electrical circuit between solenoid valve' 5l andits connections toswitches 61 and. Manometer 85 serves as a primary control to prevent closing of the electrical circuit untila desired pressureis attained in the'absorber. It assures that the refrigeration system cannot be started until the machine is thoroughly" purged. Manometer 85 as shown in Figure 3 includes a U- shaped tube 86 having mercury 81 therein. 'Conhector rods 88 and 89' extend into tube 86. One end of tube 86 is completely evacuatedand sealed; the other end is connected to absorber" 3 byline 80. "The contacts 9| and 92 are connected into wire 15. If pressure in the absorber is too high, evincing. a need'for purging, the mercury level inthe connected end oftube 86 is forcedldown preventing. closing. of the electrical circuit. .As pressure in the absorber decreases to the predetermined point, the mercury level risesand as themercury contacts rod-89. the circuit is closed permitting the machine to'operate as described above.

It will be appreciated themanometer 85 interrupts operation of the-machine if absolute pressure in the absorber reaches a predetermined point, breaking the electrical: circuit to close'the steam and condensing. water valvesand diluting the solution as described above.

It will be appreciated solenoid v'alve'5l is connected with the starterof the chilled water pump and also: with the starter: of .the solution'pump; if. either fails. solenoil valve: 5 I1 functions to shut on the-system. It is also connected indirectly topressurestat or pressure switch 'll'dlsposed adjacent the discharge ofsolution pump=8 so that if the solution pump fails or there is a shortage of solution the solenoid valve functions to shut off the system.

It is desirable that the solution valve remain open upon shut down due to failure of some element of the system, in order that the water 6 adeldto the system from tank: 81 -i's-thoroughly. mixed-withv solutionin the system. i

If solution crystallizes in .theeeneiator under various conditions .it' may be desired to supply steam-to the'gencratormanually. For this purpose it isrnecessary. to'byepass; solenoid'valveti so that by-pass 8| andvalves' 82'and 83'may be employed. Under-these. conditions, dilution valve 38 is inoperative. The present. invention provldestas simple and inexpensive safety control for an absorption refrigeration machine assuring that operation of the-machine will be discontinued upon failure of the control elements or the circulating pumps and motors therefor. The safety controlv provided by thisinvention permits automatic dilution of solution upon shut down. The-safety control-so provided is economical and maybe readily included=in the control arrangement of the machine during manufacture or after the machines are employed in the'field.

" While I have described and illustrated a'preferredembodiment of my invention, it will be understood that my invention is not limited thereto since it may be otherwise embodied with-' in the scope of the following claims:

I claim:

L'In an absorption refrigeration system, the combination of an absorber, an evaooratona generator and a condenser disposed in a closed circuit; means'for regulating flowof solution through the circuit; means for-regulating supply of heating medium to the generator; means for regulating supply'of cooling "medium to the absorber and condenser, a pneumatic supply system for actuating the-regulating means, means for reflecting a predetermined increase in temperature of chilled water leaving the evaporator. and means for'ventingat least aportion of the pneumatic supply system to the atmosphere to discontinue operation of the absorption system, said venting means being actuatedby said" reflecting means.

2.? In an absorptionrefrigeration system, the combination ofan absorber, an'evaporatorpa generator ands: condenser disposed in a closed circuit; means for regulating flow of solution through the circuit; means for regulating supply of 'heating'medium to the generator,'means' for regulating supply of cooling medium to the"absorber and condenser, a pneumatic supply system for actuating the regulating means, and means for 'venting'toa'tmosphere compressed air supplied to the heating and cooling regulating means to discontinue supply of heating medium to the generator and supply of cooling. medium to' the absorber and the? condenser.

3.In an-absorption refrigeration system, the combination of an absorber; an evaporator, a generator and a condenser disposedin a closed circuit. a valve in the circuit regulating flow of solution through thecircuit, means for regulating supply of heating medium to the generator, means for regulating supply of cooling medium to the absorber and the condensena pneumatic supply system for actuating said valve, said heatingmediumregulating means and said-cooling medium regulating means, and a safety control fordiscontinuingoperation of the refrigeration system; said safety control including an operating switch, a second switch responsive to a predetermined increase in temperature of chilled water leaving the evaporator and means in the pneumatic supply system for venting compressed air therein to the atmosphere whereby upon a 4. In an absorption refrigeration system, the

combination of an absorber, an evaporator, a

generator and a condenser disposed in a closed circuit, means for regulating flow of solution through the circuit, means for regulating the supply of heating medium to the generator, means for regulating supply of cooling medium to the absorber and to the condenser, a pneumatic supply system for actuating said means, said pneumatic supply system including a supply line for compressed air and secondary lines connecting the supply line with said regulating means, a three-way solenoid valve disposed in said supply line, an operating switch, a second switch, an electrical circuit including the solenoid valve and first and second switches, said second switch serving in response to a predetermined increase in the temperature of chilled water leaving the evaporator to break the electrical circuit thereby closing the solenoid valve and permitting compressed air in the pneumatic supply system to vent to atmosphere.

5. In an absorption refrigeration system, the combination of an absorber, an evaporator, a generator and a condenser disposed in a closed circuit, a valve for regulating flow of solution through the circuit, a thermostat for actuating said valve in response to load conditions, means for regulating supply of heating medium to the generator, means for regulating supply of cooling medium to the absorber and to the condenser, a pneumatic sup-ply system for supplying compressed air to the valve, the thermostat and said regulating means, said pneumatic supply system including a supply line and secondary lines connected to said regulating means, a solenoid valve disposed in said supply line to control supply of compressed air to said regulating means, a secondary line connecting the supply line with said solution regulating valve and said thermostat, said secondary line being disposed between the source of supply of compressed air and said solenoid valve, an operating switch, and a control switch for said solenoid valve respon sive to a predetermined increase in temperature of chilled water leaving the evaporator whereby upon a predetermined increase in temperature of chilled water leaving the evaporator the solenoid valve is closed to discontinue supply of compressed air to said regulating means, while permitting continued supply of compressed air to said valve and to said thermostat.

6. An absorption refrigeration system according to claim 3 in which a manometer is provided to prevent operation of the system until pressurein the absorber has reached a predetermined low point.

7. In an absorption refrigeration system, the combination of an absorber, an evaporator, a generator and a condenser disposed in a closed circuit, means for circulating solution through the circuit, a valve in said circuit for regulating the passage of solution through the circuit, a thremostat for controlling said valve in response to load conditions, a second valve for regulating passage of steam to the generator, a third valve for regulating passage of cooling water through the absorber and the'condenser, a second control for regulating said second valve, a third control for regulating said third valve, a pneumatic supply system for supplying compressed air to operate said controls and means for venting at least a portion of the pneumatic supply system to the atmosphere to discontinue operation of the absorption system.

8. In an absorption refrigeration system, the combination of a first shell, a first element in the shell cooperating therewith to form an absorber, a second element in said shell cooperating therewith to form an evaporator, a second shell, a first element in said second shell cooperating therewith to form a generator, a second element in said second shell cooperating therewith to form a condenser, said absorber, evaporator, generator and condenser being disposed in a closed circuit, means for passing solution through said circuit, a pneumatically operable control regulating passage of solution through the circuit, a second pneumatically operable control regulating supply of heating medium to the enerator, a third pneumatically operable control regulating supply of cooling medium to the absorber and the condenser, a pneumatic supply system, means for venting at least a portion of the pneumatic supply system to the atmosphere to discontinue operation of the refrigerating system and a safety control responsive to a predetermined increase in temperature of chilled water leaving the evaporator, said safety control including the venting means in the supply line of the pneumatic supply system, an operating switch and a control switch responsive to a predetermined increase in temperature of chilled water leaving the evaporator, an electrical circuit connecting the venting means, operating switch and control switch, said control switch in response to a predetermined increase in temperature of chilled water leaving the evaporator breaking the electrical circuit to vent compressed air from the pneumatic supply system to the atmosphere and to discontinue supply of compressed air to the heating and cooling medium controls.

9. A safety control for an absorption refrigeration system including pneumatically operable controls, the combinatiion of a solenoid valve disposed in an air supply line to at least some of said controls, a switch, an electrical circuit including the solenoid valve and the switch, means for actuating the switch in response to a predetermined increase in temperature of chilled water leaving the evaporator of the system to break the electrical circuit thereby closing the solenoid valve and discontinuing air supply to the controls supplied therethrough.

' LOUIS H. LEONARD, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,287,441 McGinnis June 23, 1942 2,298,924 Bichowsky Oct. 13, 1942 2,461,513 Berestneff Feb. 15, 1949 2,470,756 Berestneif May 24, 1949 

